window.onload = function(){
  let b3 = document.getElementsByClassName('b3')[0]

  console.log(b3);
  let x = b3.getBoundingClientRect().left
  console.log(x);
  let y = b3.getBoundingClientRect().top
  console.log(y);
  let a = window.screenX
  let b = window.screenY
  console.log(a, b);

  let sreen = window.screen.height

  let scrollHeight = document.documentElement.scrollTop
  console.log((scrollHeight + sreen) / 1.3)


  window.onscroll = () => {
    console.log('red');
    let sreen = window.screen.height

    let scrollHeight = document.documentElement.scrollTop
    console.log((scrollHeight + sreen) / 1.3)
  }
}

